The presence of decreased insulin action or insulin resistance is one of the many different pathogenetic mechanisms existent in patients with hypertension. In addition to an effect on blood pressure, hyperinsulinemia may be an independent risk factor for CAD. The beneficial effects of certain antihypertensives may extend beyond the lowering of the blood pressure since they may alter insulin sensitivity. This study will refine our understanding of the effects of antihypertensives on insulin sensitivity in patients with NIDDM.